MAP2K4 and Parkinson disease: In PD, AS‐Exos released exosomes with miR‐200a‐3p to neurons, targeting MKK4 by binding to two independent sites on the 3'‐UTR of Map2k4/MKK4 mRNA, attenuating cell death in MPP‐treated SH‐SY5Y cells and glutamate‐treated hippocampal neuronal cultures [155].